Adding diff patch html for description fields

requirements.txt

@@ -18,6 +18,7 @@ pygments>=1.6
 django-sites==0.4
 Markdown==2.4
 fn==0.2.13
+diff-match-patch==20110725.1
 
 # Comment it if you are using python >= 3.4
 enum34==0.9.23

taiga/mdrender/service.py

@@ -32,6 +32,9 @@ def _make_extensions_list(wikilinks_config=None):
             "codehilite"]
 
 
+import diff_match_patch
+
+
 def cache_by_sha(func):
     @functools.wraps(func)
     def _decorator(project, text):
@@ -71,5 +74,23 @@ def render(project, text):
     renderer = F() >> F(_preprocessors, project) >> F(_render_markdown, project) >> F(_postprocessors, project)
     return renderer(text)
 
+class DiffMatchPatch(diff_match_patch.diff_match_patch):
+    def diff_pretty_html(self, diffs):
+        html = []
+        for (op, data) in diffs:
+          text = (data.replace("&", "&amp;").replace("<", "&lt;")
+                     .replace(">", "&gt;").replace("\n", "<br />"))
+          if op == self.DIFF_INSERT:
+            html.append("<ins style=\"background:#e6ffe6;\">%s</ins>" % text)
+          elif op == self.DIFF_DELETE:
+            html.append("<del style=\"background:#ffe6e6;\">%s</del>" % text)
+          elif op == self.DIFF_EQUAL:
+            html.append("<span>%s</span>" % text)
+        return "".join(html)
 
-__all__ = ['render']
+def get_diff_of_htmls(html1, html2):
+    diffutil = DiffMatchPatch()
+    diff = diffutil.diff_main(html1, html2)
+    return diffutil.diff_pretty_html(diff)
+
+__all__ = ['render', 'get_diff_of_htmls']

taiga/projects/history/services.py

@@ -39,6 +39,7 @@ from django.contrib.contenttypes.models import ContentType
 from .models import HistoryType
 
 from taiga.mdrender.service import render as mdrender
+from taiga.mdrender.service import get_diff_of_htmls
 
 # Type that represents a freezed object
 FrozenObj = namedtuple("FrozenObj", ["key", "snapshot"])
@@ -155,6 +156,13 @@ def make_diff(oldobj:FrozenObj, newobj:FrozenObj) -> FrozenDiff:
         if key not in first:
             diff[key] = (not_found_value, second[key])
 
+    if "description" in diff:
+        description_diff = get_diff_of_htmls(
+            diff["description"][0],
+            diff["description"][1]
+        )
+        diff["description_diff"] = (not_found_value, description_diff)
+
     return FrozenDiff(newobj.key, diff, newobj.snapshot)